Do u have any maps installed and what mods do u have. Just because your mods are not ticked does not mean they are not running. Last thing to do is unscribe from all the workshops items you have, then delete your addons folder and then verify your files for integrity. This will download a new addons folder and put everything back to new. A lot of maps have mods built into them. If the game has worked fine up until now what was the last thing you installed.